Device and method for processing data derivable from remotely detected electromagnetic radiation

ABSTRACT

The present invention relates to a device and a method for processing data derivable from remotely detected electromagnetic radiation emitted or reflected by a subject, the data comprising physiological information. An input signal is received and indicative entities thereof are transmitted, the indicative entities being indicative of physiological information representative of at least one vital parameter in a subject of interest, wherein the indicative entities are detected under consideration of at least one defined descriptive model describing a relation between physical skin appearance characteristics and a corresponding representation in the input signal such that non-indicative side information represented by non-indicative entities in the input signal is substantially undetectable in a resulting transmitted signal. The at least one vital parameter is detected from the transmitted signal comprising the indicative entities, wherein the at least one vital parameter is extracted under consideration of detected skin color properties representing circulatory activity.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional application Ser.No. 61/703,828 filed Sep. 21, 2012 and EP provisional application serialno. 12185452.5 filed Sep. 21, 2012, both of which are incorporatedherein by reference.

FIELD OF THE INVENTION

The present disclosure relates to a device and method for processingdata derivable from remotely detected electromagnetic radiation emittedor reflected by a subject, wherein the data comprises physiologicalinformation. More specifically, the present disclosure relates to imageprocessing devices and methods for detecting and monitoring vitalparameters in a subject of interest. More particularly, but likewisenon-restricting, the present disclosure may further relate tophotoplethysmographic and, even more specifically, to remotephotoplethysmography approaches. The present disclosure further relatesto a computer readable non-transitory medium.

BACKGROUND OF THE INVENTION

WO 2011/021128 A2 discloses a method and a system for image analysis,including:

-   obtaining a sequence of images;-   performing a vision-based analysis on at least one of the sequence    of images to obtain data for classifying a state of a subject    represented in the images;-   determining at least one value of a physiological parameter of a    living being represented in at least one of the sequence of images,    wherein the at least one value of the physiological parameter is    determined through analysis of image data from the same sequence of    images from which the at least one image on which the vision-based    analysis is performed is taken; and-   classifying a state of the subject using the data obtained with the    vision-based analysis and the at least one value of the    physiological parameter.

The document further discloses several refinements of the method and thesystem. For instance, the use of remote photoplethysmographic (PPG)analyses is envisaged.

Basically, photoplethysmography and related vision-based imagingapproaches are considered as conventional techniques which can be usedto detect physiological information and, based thereon, vital signals orparameters in a subject of interest. Typically, the vital parameters arederived in a mediate way. Vital parameter detection can be based on thedetection of volume changes of organs or organ components in a livingbeing (or: subject of interest). More specifically, in some cases,photoplethysmography can be considered as an optical technique which canbe utilized to detect blood volume changes in the microvascular portionof the subject's tissue. Typically, photoplethysmographic measurementsare directed at the skin surface of the subject. Conventionally knownPPG approaches include so-called contact PPG devices which can beattached to the skin of the subject, for instance to a finger tip.Generally, the detected PPG signal (or: waveform) typically comprises apulsatile physiological waveform attributable to cardiac synchronouschanges in the blood volume with every heartbeat. Besides this, the PPGwaveform can comprise further physiological information attributable torespiration, oxygen saturation, Traube-Mayer-Hering waves, and even tofurther physiological phenomena.

Recently, so-called remote photoplethysmography has made enormousprogress in that unobtrusive non-contact remote measurements based onconventional cameras have been demonstrated. The term “conventionalcamera” may refer to off-the-shelf cameras, for instance digital videocameras, digital (photo) cameras providing video recordingfunctionality, or even to integrated cameras in desktop computers,mobile computers, tablets and further mobile devices, such assmartphones. Furthermore, so-called webcams attachable to computingdevices may be covered by the term “conventional camera”. Furthermore,also medical monitoring devices, video conferencing systems and securitysurveillance devices can make use of standard camera modules.

Typically, these cameras can comprise responsivity (or: sensitivity)characteristics adapted to the visible portion of the electromagneticspectrum. As used herein, visible radiation may be defined by thegeneral radiation perception ability of the human eye. By contrast,non-visible radiation may refer to spectral portions which are notvisible to a human's eye, unless optical aid devices convertingnon-visible radiation into visible radiation are utilized. Non-visibleradiation may relate to infrared radiation (or: near-infrared radiation)and to ultraviolet (UV) radiation. It should be understood that in somecases, conventional cameras may also be sensitive to non-visibleradiation. For instance, a camera's responsivity range may cover thewhole visible spectrum and also adjacent spectral portions belonging tothe non-visible spectrum or, at least, to a transition area between thevisible and the non-visible spectrum. Still, however, exemplarilyreferring to night vision applications and thermal imaging applications,also cameras primarily directed at non-visible portions of theelectromagnetic spectrum can be envisaged.

Nowadays, digital technology gains even further significance in everydaylife. By way of example, images and sequences thereof are digitallyrecorded, processed and reproduced, and can be duplicated without loss.An individual may be confronted with digital imaging devices in public(e.g., traffic monitoring, security monitoring, etc.), in private life(e.g., mobile phones, mobile computing devices including cameras), whendoing sports or work-outs (e.g., heart rate monitoring, respirationmonitoring applying remote PPG techniques), at work (e.g., vision-basedmachine or engine monitoring, fatigue monitoring or drowsinessmonitoring, vision-based access control, etc.), and even in healthcareenvironments (e.g., patient monitoring, sleep monitoring, etc.).Consequently, regardless of whether the individual is aware or unawareof being monitored in the individual case, a huge amount of (image) datacan be gathered in everyday life.

It is an object of the present invention to provide a system and amethod for processing data addressing the above-mentioned issues andenhancing privacy preservation while still allowing for an extraction ofvital signals from the recorded data. Furthermore, it would beadvantageous to provide a system and a corresponding method configuredfor hiding privacy related information which is not necessarilyessential to the vital signal extraction. It would be further desirableto provide a computer program configured for implementing said method.

In a first aspect of the present disclosure a device for processing dataderivable from remotely detected electromagnetic radiation emitted orreflected by a subject is presented, the data comprising physiologicalinformation, the device comprising:

-   -   a signal detector unit configured for receiving an input signal        and for transmitting indicative entities thereof, the indicative        entities being indicative of physiological information        representative of at least one vital parameter in a subject of        interest; and    -   a processing unit configured for extracting the at least one        vital parameter from a transmitted signal comprising the        indicative entities, wherein the at least one vital parameter is        extracted under consideration of detected skin-colored        properties representing circulatory activity;    -   wherein the signal detector unit is further configured for        detecting the indicative entities under consideration of at        least one defined descriptive model describing a relation        between physical skin appearance characteristics and a        corresponding representation in the input signal such that        non-indicative side information represented by non-indicative        entities in the input signal is substantially undetectable in        the resulting transmitted signal.

The present disclosure addresses privacy preservation issues by treatingnon-indicative entities in the input signal in such a way thatsubstantially no conclusions regarding personal or privacy informationcan be drawn therefrom. It is acknowledged in this connection that theindicative signal entities indeed may also comprise privacy-relatedinformation. However, the indicative entities are considered essentialfor the vital parameter extraction the device is targeted at. Basically,the indicative entities may represent skin portions of the subject ofinterest. It is worth mentioning in this connection that also aplurality of subjects can be present in or represented by the inputsignal. Consequently, also the indicative entities may be representativeof the plurality of subjects.

The non-indicative entities may cover surroundings or environmentalinformation. The non-indicative entities may further comprisenon-indicative information (in terms of the at least one vital parameterof interest) which is still closely related to the observed subject'sprivacy. This may involve clothing information and housing information.Consequently, also the so-called non-indicative side information cancomprise privacy information. By way of example, the non-indicative sideinformation may indicate an individual's personal wealth status.Furthermore, a usual place of residence or a current whereabout might beextracted from the non-indicative side information. It is thereforeconsidered beneficial that the non-indicative entities are substantiallydisregarded during further processing.

It is understood that also the indicative entities in the input signalmay comprise personal or privacy information. Still, given that signalportions formed by the indicative entities can basically be taken out ofthe overall context or representation observed by the signal detectorunit, privacy preservation can be improved. By way of example, primarilyindicative skin portions of the subject of interest can remain in theresulting transmitted signal. Assuming that clothing information,housing information and further side information representative ofsurroundings are no longer detectable in the resulting transmittedsignal, the risk of privacy information losses or even privacyinformation misuse can be reduced significantly.

As used herein, in some embodiments, the term “circulatory activity” mayrefer to cardiovascular activity or, in general, to vascular activity.It should be understood that also respiratory activity is closelyrelated to vascular activity. Consequently, the at least one vitalparameter can represent the subject's heartbeat, heart rate, heart ratevariability, respiration rate, respiration rate variability, pulseoxygen saturation, and suitable derivates and combinations thereof. In apreferred embodiment the processing unit can make use ofphotoplethysmographic or, even more preferred, remotephotoplethysmographic approaches. Basically, circulatory activity of thesubject can be monitored in a mediate way through observing thesubject's skin. Slight fluctuations of skin appearance, such as skincolor fluctuations, can be attributed to vascular activity, for example.

As used herein, each of the terms “indicative entities” and“non-indicative entities” may refer to particular signal fractions orelements (in terms of an observed area). It is worth noting that each ofthe indicative entities and the non-indicative entities may refer to atleast a single area element or to a set of area elements. By way ofexample, given that the input signal is encoded in (digitized) datarepresentative of vision-based information or image information, therespective entities may refer to at least a pixel or to a set of pixels.For instance, when a sequence of signal samples (or: image samples) isprocessed, each of the indicative entities and the non-indicativeentities may be formed of respective portions in the samples. Assumingthat the input signal is still embodied in form of electromagneticradiation, the indicative entities and the non-indicative entities mayrefer to respective portions of the observed area. Also in this caseboth the indicative entities the non-indicative entities can be formedof a respective signal sub-portion or of a respective set ofsub-portions.

The at least one defined descriptive model can be embodied by a modelfor (directly or indirectly) describing skin in terms of electromagneticradiation. It is preferred in some embodiments that the descriptivemodel is a human skin representation model or, more specifically, ahuman skin color model.

According to a further aspect, the signal detector unit comprises atleast one color filter element comprising a filter response adapted tospectral properties corresponding to the at least one descriptive model.The at least one filter element can be embodied by at least one opticalfilter. The at least one color filter element can also comprise a colorfilter array comprising a plurality of single filter elements. The atleast one color filter element can be configured in such a way thatbasically indicative entities may pass the respective filter elementwhile non-indicative entities are blocked, or at least, attenuated. Itis preferred that the at least one filter element is configured forstopping non-indicative entities. By way of example, the at least onecolor filter element can comprise filter characteristics adapted to skincolor properties. In this way, skin-indicative entities may pass whilenon-skin entities can be blocked, suppressed, or stopped.

The at least one color filter element can be formed by at least oneoptical lens filter, for example. In the alternative, the at least onecolor filter element can be embodied by at least one semiconductoroptics filter element. By way of example, the at least one color filterelement can be embodied by a Bayer filter array making use of aplurality of semiconductor filters. In this way, incoming signals can befiltered at the level of the sensor device before being converted intodigital data. Therefore, no digital representation or, if at all, merelya manipulated representation of the non-indicative entities can beencoded or present in captured digital signals. In other words, thedevice can make use of a sensor means to which a respective input filterelement is coupled which filters input radiation such that basicallyskin-indicative entities may pass, while non-skin entities are blocked,or, at least, attenuated.

According to yet another aspect the input signal comprises an inputsequence of signal samples, wherein the signal detector unit comprisesat least one data processing detector configured for processingrespective signal samples of the input sequence under consideration ofspectral information embedded in signal sample entities, therebygenerating a transmitted signal sequence, wherein the at least one dataprocessing detector is further configured for detecting the indicativeentities under consideration of the at least one descriptive modeldescribing a relation between physical appearance characteristics and acorresponding data representation in the signal samples.

This aspect can make use of digital data processing of an input sequencealready captured and encoded (into digital data) in advance. A suitableanalogue-digital converter can be formed by a respective sensor means,for instance, a camera. To this end, for instance, CCD-cameras andCMOS-cameras can be envisaged. Consequently, a basically discretesequence of signal samples (or: frames) can be captured and delivered tothe signal detector unit.

According to this aspect, each entity may comprise at least a singlepixel or a set of pixels. It is worth mentioning in this connectionthat, by detecting or identifying indicative pixels in the signalsamples, vice versa, also the non-indicative entities can be identified,at least in a mediate way. Consequently, each of the signal samples inthe input sequence can be segmented into at least one indicative portionand at least one non-indicative portion. It is preferred that the atleast one non-indicative portion (which indeed can be indicative ofprivacy information) is excluded from further signal processing ordistribution measures.

The at least one descriptive model may provide a link between physicalskin appearance characteristics in terms of electromagnetic radiationcharacteristics and a corresponding digital data representation makinguse of signal encoding conventions for visual signals in digital data.

According to yet another aspect the device may further comprise amasking unit configured for masking respective non-indicative entitiesin the transmitted signal sequence, wherein the data processing detectoris further configured for classifying entities into one of an indicativestate and a non-indicative state. For instance, the data processingdetector can be configured to flag respective pixels in the signalsamples. In this way, at least one of an indicative state and anon-indicative state can be assigned to respective pixels and,consequently, to respective entities. To this end, the data processingdetector can make use of a skin classifier or, more particularly, of askin pixel classifier.

Eventually, a transmitted signal can be obtained which is based on theinput signal sequence and still comprises indicative entities orportions. On the contrary, the transmitted signal sequence may furthercomprise masked portions or entities which may replace non-indicativeentities. By way of example, the masking unit can be configured forassigning a constant (color) value to non-indicative entities.Furthermore, according to an alternative aspect, the masking unit can beconfigured for blurring non-indicative pixels, or, more preferably,non-indicative portions comprising a plurality of non-indicative pixels.Typically, blurred portions may sufficiently hide underlyingprivacy-related information. As used herein, the term blurring may referto various image manipulating measures directed at reducing (privacy)information content. It can be envisaged in this connection that furtherimage or data manipulating measures can be applied to non-indicativeportions of the signal samples so as to hide respective privacyinformation.

According to yet an even further aspect the signal samples are encodedunder consideration of a signal space convention applying a color model,wherein an applied signal space comprises complementary channels forrepresenting the entities forming the signal samples, wherein respectivecomponents of the entities are related to respective complementarychannels of the signal space.

Typically, digital image representation requires an A/D(analogue/digital) conversion under consideration of a predefinedconversion convention. In other words, the entities in the signalsamples may comply with a signal space convention which basicallydescribes a relation between electromagnetic radiation characteristicsand respective signal properties of the entities in the (digital) signalsamples. Typically, a signal space or color space may involve acombination of a color model and a respective mapping function which isutilized for data generation. Generally, the signal space may comprisetwo or more dimensions. A single pixel in a signal sample may berepresented by a value or a respective vector (herein also referred toas index element) in the signal space.

In some embodiments, the signal space is an additive color signal space,wherein the complementary channels are additive color channels, whereinthe entities are represented by at least three absolute components,wherein the at least three absolute components represent distinct colorcomponents indicated by the additive channels, and wherein the additivechannels are related to define spectral portions. Such a color space maybe embodied by an RGB color space, or by derivates thereof. Furthermore,subtractive color signals spaces can be envisaged, for instance, a CMYKcolor space, and respective derivates. Still, alternatively, the signalspace can be configured as a signal space basically indicative ofluminance information and chrominance information. This may apply, forinstance, to the YUV color space.

According to a further aspect the signal space comprises a colorrepresentation basically independent of illumination variations. Itshould be noted in this connection, that also a “reduced” signal spacemay be utilized for detecting the indicative entities and, respectively,the non-indicative entities in the signal samples. By way of example, asubspace of the YUV signal space can be utilized to this end.Furthermore, signal spaces can be converted into derivative signalspaces in which luminance information is basically disregarded. By wayof example, an additive color signal space (such as RGB) can be “mapped”to a chromaticity plane which may provide for color propertyrepresentation regardless of actual luminance. In this way, luminancenormalization can be achieved. Consequently, the detection of theindicative entities can be facilitated. For instance, respectiveR-values, G-values and B-values of the RGB signal space can be dividedby a predefined linear combination of R, G and B, respectively. Such anormalization can further provide for a dimensional reduction.Preferably, the descriptive model or skin model makes use of the signalspace in that an underlying vision-based skin model is defined andexpressed in terms of the respective signal space convention.

According to another aspect it is further preferred that the descriptivemodel is a skin color model describing skin representation underconsideration of signal space conventions. By way of example, thedescriptive model can make use of look-up table data for comparisonmeasurement and classification. The look-up table data may comprise avariety of predefined values representing indicative entities. Accordingto one embodiment, the descriptive model is an explicit skin model. Anexplicit skin model may comprise a defined subspace of a signal spacewhich is considered attributable to a representation of the subject'sskin, for example. However, in the alternative, the descriptive modelcan be at least one of a non-parametric skin model and a parametric skinmodel.

By way of example, a non-parametric skin model can be based on a look-uptable comprising a plurality of histograms representing a variety ofreference measurements. A parametric skin model can make use of asimplified function-type representation of classification data in thesignal space. By way of example, based on histograms obtained throughreference measurements, Gaussian functions can be defined for describinga probability distribution with regard to whether or not a given entity(or: pixel) can be considered as an indicative entity or anon-indicative entity. In this connection, single Gaussian and multipleGaussian functions can be envisaged.

According to another advantageous aspect, the masking unit is furtherconfigured for processing the indicative entities such that the at leastone vital parameter is substantially detectable in the transmittedsignal sequence, wherein non-indicative side information represented bythe indicative entities is at least partially attenuated in thetransmitted signal sequence. In this context, processing the indicativeentities may involve blurring sets of indicative entities.

This embodiment is based on the idea that also the indicative entitiescan be processed so as to further enhance privacy preservation. It ispreferred in this connection that processing parameters are chosen suchthat the to-be-extracted vital parameter is substantially preserved inthe processed samples. Since vital parameter extraction may involvespatially averaging indicative regions of interest, blurring operationsor similar algorithms can be applied to the indicative entities,provided that respective average values of interest (e.g., spatial meanpixel color values) remain substantially unchanged. By way of example, ablurring algorithm (e.g., Gaussian blur) can be applied to theindicative entities. In this way, privacy-related information, such asskin details, etc., can be diminished or attenuated while vitalparameter-indicative information can be preserved, that is, forinstance, a mean pixel color in an indicative region of interest is notaffected. Consequently, mean pixel color fluctuations can be preservedfor further analysis. By way of example, spatial blurring involvingselective filter algorithms may be applied to the regions comprising theindicative entities.

It is further preferred in this connection that blurring parameters(e.g., blurring filter characteristics) are chosen such that indicativeentities or sets of indicative entities comprising high contrast (hugedifferences in luminance and/or color) are excluded from blurringoperations. High contrast areas may adversely influence average valuesand may therefore distort processed vital parameter-representativesignals.

It is further envisaged to apply blurring operations or similar imageprocessing operations to both the indicative entities and thenon-indicative entities. In this connection, however, it is preferredthat regions comprising the indicative entities and regions comprisingthe non-indicative entities are processed separately so as to avoidblending or mixing up indicative entities and non-indicative entities.

According to yet another aspect, the device further comprises a databaseproviding a plurality of descriptive models attributable to an influenceparameter selected from the group consisting of skin color type, ethnicregion, ethnic group, body region, sex, sensor unit characteristics, andillumination conditions, and combinations thereof.

According to this approach the device can make use of a descriptivemodel currently considered suitable for an actual monitoringenvironment. The plurality of descriptive models may comprise aplurality of non-parametric skin models. In this case, even thoughnon-parametric skin models can be considered somewhat inflexible orstatic, the device as a whole can be adapted to varying monitoringconditions.

According to an alternative exemplary aspect the signal detector unit isfurther configured for adapting the present descriptive model underconsideration of an influenced parameter selected from the groupconsisting of skin color type, ethnic region, ethnic group, body region,sex, sensor unit characteristics, and illumination conditions, andcombinations thereof. By way of example, a parameter of a parametricskin model can be adjusted accordingly so as to adapt the descriptivemodel to given monitoring conditions. It is worth mentioning in thisconnection that the above influence parameters basically may influencethe appearance and the perception of skin colors and, therefore, mayalso influence accuracy of the indicative entity detection.

According to still yet a further aspect the device further comprises asensor unit, in particular a camera, configured for sensingelectromagnetic radiation at a distance, wherein the sensor unit iscoupled to the signal detector unit such that non-indicative entities inthe input signal are basically disregarded when transmitting respectivesignal samples. By way of example, a camera can be integrated in thedevice such that no external excess to a captured input sequence isallowed.

According to yet another aspect the sensor unit comprises a responsecharacteristic adapted to the descriptive model such that non-indicativeentities are basically disregarded when capturing the signal samples. Inthis connection, the detector unit and the masking unit can beimplemented in the camera, for instance, via optical components,(digital) data processing components, and combinations thereof.

According to yet another aspect the device may further comprise anoutput interface for distributing the sequence of processed samples. Thesequence of processed samples in which non-indicative entities arebasically undetectable can be forwarded, distributed or copied withoutthe risk of revealing non-indicative side information.

According to a further aspect the device further comprises a featuredetector configured for detecting identity-related prominent features insignal samples of the input sequence, and a feature masking unitconfigured for masking respective entities in the transmitted signalsequence. This embodiment may even further contribute in enhancingprivacy preservation. By way of example, the feature detector can beconfigured for applying eye recognition, face recognition, mouthrecognition, hair recognition, and combinations thereof. Since primarilyskin portions in the subject of interest are addressed, additionalprominent features which may be considered even further indicative ofprivacy-related information (rather than of vital parameters ofinterest) can be detected and removed from the respective signal sample.

According to yet an even further aspect the processing unit is furtherconfigured as photoplethysmographic processing unit capable ofextracting the at least one vital parameter of interest from thesequence of transmitted samples, wherein the at least one vitalparameter can be extracted under consideration of vascular activityrepresented by skin color properties.

There exist several embodiments of the signal detector unit and theprocessing unit and, if any, of respective subcomponents thereof. In afirst, fairly simple embodiment the signal detector unit and theprocessing unit as well as their respective (data processing)subcomponents can be embodied by a common processing device which isdriven (or: controlled) by respective logic commands Such a processingdevice may also comprise suitable input and output interfaces. However,in the alternative, each of the signal detector unit and the processingunit can be embodied by separate processing devices controlled orcontrollable by respective commands. Hence, each respective processingdevice can be adapted to its special purpose. Consequently, adistribution of tasks can be applied, wherein distinct tasks areprocessed (or: executed) on a single processor of a multi-processorprocessing device or, wherein image processing related tasks areexecuted on an image processor while other operational tasks areexecuted on a central processing unit. The above may also refer tosubcomponents of the signal detector unit and the processing unit. Eachof the processing unit, the signal detector unit and their respectivesubcomponents can be implemented as a virtual part of a processingenvironment or as a discrete (e.g., hardware-coded) processing element.Hybrid implementations can be envisaged.

In a further aspect of the disclosure a method for processing dataderivable from remotely detected electromagnetic radiation emitted orreflected by a subject is presented, the data comprising physiologicalinformation, the method comprising the steps of:

-   receiving an input signal and transmitting indicative entities    thereof, the indicative entities being indicative of physiological    information representative of at least one vital parameter in a    subject of interest;-   detecting the indicative entities under consideration of at least    one defined descriptive model describing a relation between physical    skin appearance characteristics and a corresponding representation    in the input signal such that non-indicative side information    represented by non-indicative entities in the input signal is    substantially undetectable in a resulting transmitted signal; and-   extracting the at least one vital parameter from the transmitted    signal comprising the indicative entities, wherein the at least one    vital parameter is extracted under consideration of detected skin    color properties representing circulatory activity.

Advantageously, the method can be carried out utilizing the device forextracting information of the disclosure.

In yet another aspect of the present disclosure, there is provided acomputer readable non-transitory medium having instructions storedthereon which, when carried out on a computer, cause the computer toperform the steps of a method in accordance with the present disclosure.The program code (or: logic) can be encoded in one or morenon-transitory, tangible media for execution by a computing machine,such as a computer. In some exemplary embodiments, the program code maybe downloaded over a network to a persistent storage from another deviceor data processing system through computer readable signal media for usewithin the device. For instance, program code stored in a computerreadable storage medium in a server data processing system may bedownloaded over a network from the server to the device. The dataprocessing device providing program code may be a server computer, aclient computer, or some other device capable of storing andtransmitting program code.

As used herein, the term “computer” stands for a large variety ofprocessing devices. In other words, also mobile devices having aconsiderable computing capacity can be referred to as computing device,even though they provide less processing power resources than standarddesktop computers. Furthermore, the term “a computer” may also refer toa distributed computing device which may involve or make use ofcomputing capacity provided in a cloud environment.

Preferred embodiments of the invention are defined in the dependentclaims. It should be understood that the claimed method and the claimedcomputer program can have similar preferred embodiments as the claimeddevice and as defined in the dependent device claims.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention will be apparent from andelucidated with reference to the embodiments described hereinafter. Inthe following drawings

FIG. 1 shows a schematic illustration of a first general layout of adevice according to the present disclosure;

FIG. 2 shows a schematic illustration of an alternative layout of adevice according to the present disclosure;

FIG. 3 shows yet another schematic illustration of an alternative layoutof a device according to the present disclosure;

FIGS. 4 a, 4 b show an exemplary input signal sample comprisingindicative entities and non-indicative entities; and a respective(processed) transmitted signal sample in which the non-indicativeentities are substantially undetectable;

FIG. 5 shows a schematic illustration of yet an even further alternativelayout of a device according to the present disclosure;

FIGS. 6 a, 6 b show a signal sample section illustrating a subject ofinterest; and a respective section of a (processed) transmitted signalsample in which prominent features in the subject are masked; and

FIG. 7 shows an illustrative block diagram representing several steps ofan embodiment of a method in accordance with the disclosure.

DETAILED DESCRIPTION OF THE INVENTION

The following section describes exemplary approaches to remote vitalsignal detection, in particular remote photoplethysmography (remotePPG), utilizing several aspects of the device and method in accordancewith the present disclosure. It should be understood that single stepsand features of the shown approaches can be extracted from the contextof the respective overall approach. These steps and features can betherefore part of separate embodiments still covered by the scope of theinvention.

Basic approaches to remote photoplethysmography are described inVerkruysse, W. et al. (2008), “Remote plethysmographic imaging usingambient light” in Optics Express, Optical Society of America,Washington, D.C., USA, Vol. 16, No. 26, pages 21434-21445. WO2011/042858 A1 discloses a further method and system addressingprocessing a signal including at least one component representative of aperiodic phenomenon in a living being.

In these and similar measurements often images or image-likerepresentations of monitored subjects are captured. Typically, also theimage background which is not indicative of the vital parameters ofinterest is still present in the captured data. Consequently sideinformation which may allow conclusions regarding the subject's privacycan still be extracted from the recorded data. As used herein, the term“side information” typically refers to information which is notindicative of the vital parameters of interest but which may stillcontain privacy-related information.

FIG. 1 is referred to showing a schematic illustration of a device forprocessing data in a vital signal detection environment. The device isdenoted by a reference numeral 10. For instance, the device 10 can beutilized for processing image frames representing a remote subject 12for remote PPG monitoring. Typically, regions of interest 14 in thesubject 12 are targeted. At least one region of interest 14 can bepresent in a recorded frame. Typically, the region of interest 14 mayrepresent a face portion or, more generally, a skin portion of thesubject 12. By way of example, in case the subject 12 wears a T-shirtthree regions of interest 14 can be present in a captured frame, namelya head or face portion and two respective forearm portions. Needless tosay, a recorded frame may also comprise a representation of more thanone subject 12. Typically, the captured data can be derived fromelectromagnetic radiation 16 basically emitted or reflected by thesubject 12. When processing the recorded signals, eventually a vitalparameter 17 of interest can be derived from the electromagneticradiation 16. The vital parameter 17 may relate to a vital signalattributable to the subject's 12 vascular or respiratory activity.

The device 10 comprises a signal detector unit 18 and a signalprocessing unit 20. Both the signal detector unit 18 and the signalprocessing unit 20 can be implemented in a common housing 22. Thehousing 22 may also stand for a system boundary. Within the systemboundary, both the signal detector unit 18 and the processing unit 20can be arranged discretely. Furthermore, both the signal detector unit18 and the processing unit 20 can be implemented as a (single) commonintegral part of the device 10.

The device 10 illustrated in FIG. 1 can make use of at least oneupstream color filter element 28. The at least one upstream color filterelement 28 can be placed in front of at least one sensing element of asensor unit 34. Consequently, the at least one color filter element 28can be configured for receiving an input signal (directly) from theincident electromagnetic radiation 16 and transmitting a transmittedsignal 30 to the sensor unit 34. In other words, the at least one colorfilter element 28 can be configured for directly processingelectromagnetic radiation rather than processing a digital datarepresentation of electromagnetic radiation. The at least one colorfilter element 28 can comprise a respective optical filter element. Insome cases, the optical filter element can be embodied by an opticallens. Furthermore, a set of suitably arranged optical lenses can beenvisaged. However, in the alternative, or in addition, the at least onecolor filter element 28 can also be embodied by at least onesemiconductor filter element. Such a filter element can be part of aBayer filter element of, more preferably, of a Bayer filter array.Needless to say, the at least one color filter element 28 can be(physically) directly attached to the sensor unit 34.

In connection with the device 10 elucidated in FIG. 1 it is preferredthat the at least one color filter element 28 implements the at leastone descriptive model, for instance, the descriptive skin color model.That is, the at least one color filter element 28 preferably comprises afilter response which may be adapted to assumed skin representationcharacteristics in electromagnetic radiation. Consequently,non-indicative side information (non-skin entities) in the input signalcan be blocked or, at least, attenuated before being captured by thesensor unit 34.

The sensor unit 34 can be embodied by a digital camera configured forrecorded imaging frames. Such a camera can make use of CCD sensors orCMOS sensors, for example. In this way, the sensor unit 34 can implementan analogue-digital conversion of the input signals. The converted(digitized) data can be delivered to an (optional) data buffer orstorage 36. The data storage 36 may serve as a short-term cache or as along-term memory. It should be understood that the data storage 36 canform part of the signal detector unit 18 or of the processing unit 20.Furthermore, each of the signal detector unit 18 and the processing unit20 may comprise at least one data storage. Additionally, the datastorage 36 can be interposed between the signal detector unit 18 and theprocessing unit 20, refer to FIG. 3.

In FIG. 1, the processing unit 20 can receive the processed signals inwhich indicative information is still embedded, while non-indicativeinformation is basically undetectable. It is worth mentioning again inthis connection that the terms “indicative” and “non-indicative” have tobe interpreted in terms of the detection of the desired vital parameters17 of interest. By way of example, the processing unit 20 may comprise asignal extractor 38 which may be configured for applying PPG signalextraction algorithms. Consequently, a processed signal 40 can begenerated and distributed which may represent the vital parameter 17 or,at least, indicative signal entities which are highly indicative of thevital parameter 17. The arrangement shown in FIG. 1 can be considered asa privacy preserving arrangement since even though a sensor unit 34 isutilized which is basically capable of capturing indicative signalentities and non-indicative signal entities, no digital data comprisingboth the indicative entities and a plain representation of thenon-indicative entities is accessible from the outside of the systemboundary 22 of the device 10.

In FIG. 2, a similar device 10 a is presented which basically makes useof privacy preservation measures applicable to digitized imageinformation, that is, to signals downstream of the sensor unit 34. Inthis embodiment, the sensor unit 34 can be basically capable of sensinga whole portion of the electromagnetic radiation 16 (e.g., the wholevisible radiation portion) which may comprise both the indicativeentities and the non-indicative entities. In this way, an input sequence44 can be generated. Typically, the input sequence 44 comprisesdigitized data. The input sequence 44 may comprise a series of frames,more particularly, a series of image frames. The input sequence 44 canbe delivered to a processing detector 46. The processing detector 46 canbe configured for processing frames (herein also referred to as samples)of the input sequence 44. Typically, the processing detector 46 can seekfor indicative entities in the signal samples. This can be performedunder consideration of at least one descriptive model. In FIG. 2,digitized data is processed by the processing detector 46. Therefore,the at least one descriptive model may describe a relation betweenphysical appearance characteristics of indicative entities and acorresponding data representation in the (digitized) signal samples.

By way of example, the signal detector unit 18 may further comprise adatabase 48 for storing and providing the at least one descriptivemodel. However, in the alternative, the processing detector 46 can alsoimplement the at least one descriptive model which may be encoded inhardware or in software in the processing detector 46. In someembodiments, in particular when the processing detector 46 is configuredfor comparative detection of the indicative entities, the database 48may comprise look-up comparison data for classifying entities (that is,single pixels or sets of pixels) in the signal samples. In someembodiments, the processing detector 46 can be configured to “flag” theentities in the signal samples according to their classified state.

Further, downstream in the signal detector unit 18 a masking unit 50 maybe provided which can be configured for masking detected non-indicativeentities. As mentioned above, the detection of the non-indicativeentities can be carried out in a mediate way in that primarilyindicative entities are detected. Consequently, remaining entities notclassified as indicative entities can be classified as non-indicativeentities. By way of example, the masking unit 50 can be configured forreplacing the non-indicative entities in the signal samples byreplacement entities having a constant color or value. Furthermore,alternatively, the masking unit 50 can be configured for blurring thenon-indicative entities. A blurring operation or a similar imageprocessing operation is preferably applied to a considerably largeportion of the signal samples. In other words, preferably blurringoperations are applied to entities or sets of entities comprising aplurality of pixels.

In some embodiments, alternatively, or in addition, the masking unit 50can be further configured for blurring the indicative entities. It isalso preferred in this connection that considerably large (indicative)portions of the signal samples are blurred. Preferably, the masking unit50 is capable of reducing non-indicative privacy information in theindicative entities while still allowing the vital parameter of interest17 to be extracted therefrom. It should be noted in this context that ablurring operation should be separately applied to the indicativeentities and to the non-indicative entities so as to avoid mixing up therespective regions and the information embedded therein.

Upon detecting and masking non-indicative entities in the signalsamples, a transmitted sequence 52 can be generated in whichnon-indicative side information is basically undetectable. Thetransmitted sequence 52 can correspond to the input sequence 44 withrespect to frame rate and frame size (resolution). Eventually, thetransmitted sequence 52 can be delivered to the (optional) data storage36 and, consequently, to the signal extractor 38 in the processing unit20 for vital parameter extraction measures. It is preferred that thedevice 10 a is arranged in such a way that no external access to the(unprocessed) input sequence 44 is allowed. In case it is intended todistribute a sequence of signal samples without revealing unnecessaryprivacy information, the device 10 a may provide for an external accessto the transmitted sequence 52, refer to the reference numeral 54.

FIG. 3 illustrates a further alternative embodiment of a device forprocessing data and extracting physiological information which isdenoted by a reference numeral 10 b. The device 10 b is configured forcooperating with an external sensor unit 58. The sensor unit 58 can bearranged separate (or: distant) from the device 10 b. The externalsensor unit 58 can be configured for capturing an input sequence whichmay be delivered to an interface 56. It should be understood that theexternal sensor unit 58 can be used for capturing the image sequence inadvance. Consequently, the device 10 b can also be configured forprocessing an input sequence 44 which has been stored for buffered.Still, however, in some cases recording and processing the inputsequence 44 can be performed basically simultaneously. Input data can bedelivered from the external sensor unit 58 to the interface 56 viasuitable cable or wireless connections. It can be also envisaged that anexternal data storage (not shown in FIG. 3) can be coupled to theinterface 56 for delivering previously collected data.

In FIG. 3, the signal detector unit 18 does not necessarily have tocomprise an (internal) sensor unit. Instead, the input sequence 44 canbe delivered through the interface 56 to the data processing detector46. An (optional) masking unit 50 may also be provided in the signaldetector unit 18 in FIG. 3. The masking unit 50 can be consideredoptional since basically also the processing detector unit can beconfigured for masking or blocking respective non-indicative entities inthe samples of the input sequence 44 by itself The signal detector unit18 may further comprise a detector adaptor element 60. The detectoradaptor element 60 can be utilized in connection with a descriptivemodel which is configured as a parametric skin model. Consequently, thedetector adaptor element 60 can be configured for suitably adjustingparameters of the descriptive model. In particular a parametric skinmodel may comprise parameters which can be adjusted according to changesin influence parameters. An influence parameter can be selected from thegroup consisting of skin color type, ethnic region, ethnic group, bodyregion, sex, sensor unit characteristics, and illumination conditions,and combinations thereof. Consequently, either via manual operations orvia automatic (calibration) operations, a respective influence parametervariation can be detected and, consequently, the parametric skin modelcan be adjusted accordingly. Eventually, a transmitted sequence 52 canbe delivered to a respective processing unit 20, either directly orindirectly via an (optional) data storage 36.

FIG. 4 a and FIG. 4 b exemplarily illustrate an input signal sample 64and a corresponding (processed) transmitted signal sample 70. The signalsample 64 comprises a representation of a subject of interest 12exposing several regions of interest 14 a, 14 b, 14 c which can beconsidered indicative of an underlying vital parameter. Furthermore,non-indicative regions 68 in the subject 12 are present. For instance,the non-indicative region 68 can be formed by a body region covered incloths. Furthermore, the input signal sample 64 can be indicative ofsurrounding elements 66 a, 66 b which are also considered non-indicativeof the desired vital parameters. Typically, merely the regions ofinterest 14 a, 14 b, 14 c are required for the desired signalextraction. On the contrary, the surrounding elements 66 a, 66 b and thenon-indicative region 68 or, more generally, the background of thesignal sample 64, may comprise privacy-related information allowingconclusions with regard to the housing situation, the current location,the wealth status, or even the personality of the subject 12. It istherefore desirable that such add-on information (herein also referredto as side information) can be excluded from any circulation ortransmission of the respective data.

The transmitted signal sample 70 shown in FIG. 4 b can form a part ofthe transmitted sequence generated in the signal detector unit 18 uponprocessing the input sequence 44 (refer to FIGS. 2 and 3). On thecontrary, the signal sample 64 shown in FIG. 4 a can form a respectivepart of the input sequence 44. As indicated above, in the transmittedsignal sample 70 basically the regions of interest 14 a, 14 b, 14 ccomprising the indicative entities are preserved while side informationis removed from or suppressed in the transmitted signal sample 70.Consequently, a region 72 is formed in the transmitted signal sample 70which may basically be considered as a masked region, or a region ofblanks or constant values. It is worth mentioning in this connectionthat the signal entities representing the regions of interest 14 a, 14b, 14 c in FIG. 4 b may basically correspond to or have the same valuesas the respective entities in FIG. 4 a. Merely for illustrativepurposes, the regions 14 a, 14 b, 14 c are blackened in FIG. 4 b.Correspondingly, also the squared pattern of the region 72 has beenadded for illustrative purposes. It follows from FIG. 4 b that thetransmitted signal sample 70 indeed addresses privacy protectionmeasures in that unnecessary privacy-related information is no longerpresent.

FIG. 5 exemplarily illustrates a general layout of another alternativedevice for processing data and for extracting physiological information.The device 10 c may have a similar layout as the device 10 a illustratedin FIG. 2. The signal detector unit 18 of the device 10 c furthercomprises a feature detector 76 and a corresponding feature masking unit78. The feature detector 76 and the feature masking unit 78 can furthercontribute in privacy protection. To this end, the feature detector 76can be configured for detecting prominent features in the subject 12which is monitored for vital parameter extraction purposes. Featuredetection can make use of descriptive feature models describing arepresentation of prominent features in potentially indicative regionsof interest in the subject 12.

In this connection, further reference is made to FIG. 6 a and FIG. 6 b.Both FIG. 6 a and FIG. 6 b show corresponding sections of a signalsample representing a subject 12. FIG. 6 a shows a section 82 taken froman input signal sample. FIG. 6 b shows a corresponding section 86 takingfrom a transmitted sample. Feature detection can be directed atprominent features which can be considered identity-related features.For instance, features 84 a (eye region) and 84 b (mouth region) in FIG.6 b can be considered identity-related features. Advantageously, forfurther enhancing a privacy protection level, these features 84 a, 84 bcan be detected and masked or blocked such that they are substantiallyundetectable in the respective transmitted sample. The correspondingsection 86 in FIG. 6 b comprises a representation of the region ofinterest 14 which is considered highly indicative of the vital parameterof interest, while also a masked region (or: region of blanks) 72 ispresent. Furthermore, identity-related features are replaced byrespective masked portions 88 a, 88 b which basically allow noconclusions regarding the personality of the subject of interest 12.

The feature detector 76 shown in FIG. 5 can be utilized for detectingthe respective identity-related features 84 a, 84 b. The feature maskingunit 78 which may alternatively also be integrated into the featuredetector 76 may mask, suppress, or attenuate respective entities in thesignal samples so as to arrive at a transmitted sample in which merelymasked features 88 a, 88 b are present. As indicated in FIG. 5, thefeature detector 76 and the feature masking unit 78 can be configuredfor processing the input (sample) sequence 44 in parallel with the dataprocessing detector 46 and the respective masking unit 50. However,according to an alternative approach, the feature detector 76 and thefeature masking unit 78 can also be configured for processing signalsamples which have been preprocessed by the data processing detector 46and the masking unit 50. Still, also alternative processing orders canbe envisaged.

Having demonstrated several alternative exemplary approaches covered bythe disclosure, FIG. 7 is referred to, schematically illustrating amethod for processing data and for extracting physiological information.

Initially, in a step 100, an input data stream or an input sequence 102of signal samples 104 a, 104 b, 104 c is received. A time-axis isindicated by an arrow t. Each of the signal samples 104 a, 104 b, 104 cmay comprise a representation of a subject 12 of interest, and ofsurrounding elements 66 c, or, more generally, background information orside information.

A subroutine 106 may follow which is basically directed at detectingindicative entities in the signal samples 104 a, 104 b, 104 c and,consequently, at detecting also non-indicative entities. Morespecifically, the subroutine 106 can be directed at detecting skinportions and non-skin portions in the signal samples 104 a, 104 b, 104c. In a step 108 to-be-processed entities 110 in a signal sample 104 canbe selected. As indicated above, the term “entity” may stand for singlepixels or a set of pixels in the signal sample 104. In a subsequentclassifying step 120 the respective entity 110 is classified into atleast one of an indicative state and a non-indicative state. To thisend, the classifying step 120 can make use of a descriptive model 114,in particular a descriptive skin model. The descriptive model 114 cancomprise estimated characteristics of a representation of indicativeentities in the signal samples 104.

By way of example, for illustrative purposes, the descriptive model 114can comprise a probability distribution or a similar function graph orfunction surface. The descriptive model 114 can also make use of a setof (reference) histograms. In FIG. 7 the descriptive model 114 can bebased on a probability distribution such as a Gaussian distribution foran input variable e.g., a respective to-be-classified signal entity 110.The variable can be characterized by respective values in a domainformed by at least one signal channel 118 a, 118 b. By way of example,two or even more signal channels can be utilized each of which mayrepresent respective characteristics of electromagnetic radiation.Basically, a given variable may take any value within such a domain.Since the descriptive model 114 may provide for a variabilitydistribution (refer to a probability axis 116), a classification as towhether the variable is considered indicative or non-indicative can beperformed. As already indicated above, other types of descriptive modelscan be utilized. Therefore, the representation of the descriptive model114 in FIG. 7 is merely provided for illustrative purposes.

Depending on the classification outcome a step 122 or a step 124 mayfollow. In the step 122 which may follow when the entity 110 isclassified as non-indicative, the respective entity can be masked,blocked, attenuated or processed in a similar way so as to ensure thatthe non-indicative entity is basically undetectable in further signaloperation stages. In the step 124 which may follow in case therespective entity 110 is classified as an indicative entity, the entitycan be basically transmitted or allowed to pass. In this way, indicativeentities are preserved in the data for further signal processingoperations.

Regardless of the outcome of the classifying step 120 a further step 126may follow which may be directed at creating a command that a nextsignal entity 110 has to be chosen and classified unless every singleentity of the currently to-be-processed sample 104 has been classified.The respective command can be transferred to the entity selection step108. In this way, the subroutine 106 can operate loop-wise.

Having accomplished the subroutine 106, eventually a transmittedsequence 130 of transmitted samples 132 a, 132 b, 132 c can be generatedin which primarily at least one indicative region of interest 14 ispreserved. Side-information which is not necessary for vital parameterextraction measures is no longer detectable in the transmitted sequence130. In a subsequent signal derivation step 134 a characteristic signal132 can be derived from the transmitted sequence 130. To this end, therespective transmitted samples 132 can be processed so as to derivesingle values or index elements 140 on which the characteristic signal142 is based. By way of example, the single value or index element 140can represent mean characteristics of the region of interest 14 in thetransmitted sample 132. Consequently, the single value or index element140 can represent respective mean color characteristics. To this end, avectorial representation of the index element 140 can be utilized.

The index element 140 can represent a certain value within a signalspace 136, for instance, in a color space. The signal space 136 can beregarded as a convention for representing electromagnetic radiationcharacteristics in (digital) data. The signal space 136 may compriseseveral complementary channels 138 a, 138 b, 138 c. In an exemplarynon-limiting example an RBG color space can be envisaged. In thisconnection, the complementary channels 138 a, 138 b, 138 c may representrespective R-, G-, and B-channels. In combination the complementarychannels 138 a, 138 b, 138 c form the signal space 136 and therefore adomain of values the index element 140 may take. By processing aplurality of transmitted samples 132 eventually a correspondingplurality of single values or index elements 140 can be obtained whichform a basis for the characteristic signal 142. Typically, thecharacteristic signal 142 may represent slight (color) fluctuations inthe region of interest 14.

In a further subsequent signal processing step 144 signal optimizationand signal enhancement measures can be applied to the characteristicsignal 142 so as to arrive at an enhanced characteristic signal 146. Inthis connection, several signal processing measures can be envisaged,including filtering, windowing, etc. In an additional signal extractionor signal analization step 148 a vital parameter, of interest 150 can beobtained. It should be understood that in some cases basically atime-based representation and/or a frequency-based representation of thevital parameter 150 might be of interest.

By way of example, the present disclosure can be applied in the field ofhealthcare, for instance, unobtrusive remote patient monitoring, in thefield of general surveillances, e.g., security monitoring, and inso-called lifestyle environments, such as fitness equipment, or thelike. Applications may include monitoring of oxygen saturation (pulseoximetry), heart rate, blood pressure, cardiac output, changes of bloodperfusion, assessment of autonomic functions, and detection ofperipheral vascular diseases. Needless to say, in an embodiment of themethod in accordance with the disclosure, several of the steps describedherein can be carried out in changed order, or even concurrently.Further, some of the steps could be skipped as well without departingfrom the scope of the disclosure. This applies in particular to severalalternative signal processing steps. Several of the disclosedillustrative embodiments can take the form of hardware embodiments,software embodiments, or of embodiments containing both hardware andsoftware elements. Some embodiments are implemented in software whichmay include firmware and application software.

In the claims, the word “comprising” does not exclude other elements orsteps, and the indefinite article “a” or an does not exclude aplurality. A single element or other unit may fulfill the functions ofseveral items recited in the claims. The mere fact that certain measuresare recited in mutually different dependent claims does not indicatethat a combination of these measures cannot be used to advantage.

A computer program may be stored/distributed on a suitablenon-transitory medium, such as an optical storage medium or asolid-state medium supplied together with or as part of other hardware,but may also be distributed in other forms, such as via the Internet orother wired or wireless telecommunication systems.

Furthermore, the different embodiments can take the form of a computerprogram product accessible from a computer usable or computer readablemedium providing program code for use by or in connection with acomputer or any device or system that executes instructions. For thepurposes of this disclosure, a computer usable or computer readablemedium can generally be any tangible device or apparatus that cancontain, store, communicate, propagate, or transport the program for useby or in connection with the instruction execution device.

In so far as embodiments of the disclosure have been described as beingimplemented, at least in part, by software-controlled data processingdevices, it will be appreciated that the non-transitory machine-readablemedium carrying such software, such as an optical disk, a magnetic disk,semiconductor memory or the like, is also considered to represent anembodiment of the present disclosure.

The computer usable or computer readable medium can be, for example,without limitation, an electronic, magnetic, optical, electromagnetic,infrared, or semiconductor system, or a propagation medium. Non-limitingexamples of a computer readable medium include a semiconductor or solidstate memory, magnetic tape, a removable computer diskette, a randomaccess memory (RAM), a read-only memory (ROM), a rigid magnetic disk,and an optical disk. Optical disks may include compact disk—read onlymemory (CD-ROM), compact disk—read/write (CD-R/W), and DVD.

Further, a computer usable or computer readable medium may contain orstore a computer readable or usable program code such that when thecomputer readable or usable program code is executed on a computer, theexecution of this computer readable or usable program code causes thecomputer to transmit another computer readable or usable program codeover a communications link. This communications link may use a mediumthat is, for example, without limitation, physical or wireless.

A data processing system or device suitable for storing and/or executingcomputer readable or computer usable program code will include one ormore processors coupled directly or indirectly to memory elementsthrough a communications fabric, such as a system bus. The memoryelements may include local memory employed during actual execution ofthe program code, bulk storage, and cache memories, which providetemporary storage of at least some computer readable or computer usableprogram code to reduce the number of times code may be retrieved frombulk storage during execution of the code.

Input/output, or I/O devices, can be coupled to the system eitherdirectly or through intervening I/O controllers. These devices mayinclude, for example, without limitation, keyboards, touch screendisplays, and pointing devices. Different communications adapters mayalso be coupled to the system to enable the data processing system tobecome coupled to other data processing systems, remote printers, orstorage devices through intervening private or public networks.Non-limiting examples are modems and network adapters and are just a fewof the currently available types of communications adapters.

The description of the different illustrative embodiments has beenpresented for purposes of illustration and description and is notintended to be exhaustive or limited to the embodiments in the formdisclosed. Many modifications and variations will be apparent to thoseof ordinary skill in the art. Further, different illustrativeembodiments may provide different advantages as compared to otherillustrative embodiments. The embodiment or embodiments selected arechosen and described in order to best explain the principles of theembodiments, the practical application, and to enable others of ordinaryskill in the art to understand the disclosure for various embodimentswith various modifications as are suited to the particular usecontemplated. Other variations to the disclosed embodiments can beunderstood and effected by those skilled in the art in practicing theclaimed invention, from a study of the drawings, the disclosure, and theappended claims.

1. A device for processing data derivable from remotely detectedelectromagnetic radiation emitted or reflected by a subject, the datacomprising physiological information, comprising: a signal detector unitconfigured for receiving an input signal and for transmitting indicativeentities thereof; and a processing unit configured for extracting atleast one vital parameter from a transmitted signal comprising theindicative entities; wherein the indicative entities are indicative ofphysiological information representative of the at least one vitalparameter in a subject of interest; wherein the at least one vitalparameter is extracted under consideration of detected skin colorproperties representing circulatory activity; and wherein the signaldetector unit is further configured for detecting the indicativeentities under consideration of at least one defined descriptive modeldescribing a relation between physical skin appearance characteristicsand a corresponding representation in the input signal such thatnon-indicative side information represented by non-indicative entitiesin the input signal is substantially undetectable in the resultingtransmitted signal.
 2. The device as claimed in claim 1, wherein thesignal detector unit comprises at least one color filter elementcomprising a filter response adapted to spectral propertiescorresponding to the at least one descriptive model.
 3. The device asclaimed in claim 1, wherein the input signal comprises an input sequenceof signal samples, wherein the signal detector unit comprises at leastone data processing detector configured for processing respective signalsamples of the input sequence under consideration of spectralinformation embedded in signal sample entities, thereby generating atransmitted signal sequence.
 4. The device as claimed in claim 3,wherein the at least one data processing detector is further configuredfor detecting the indicative entities under consideration of the atleast one descriptive model describing a relation between physicalappearance characteristics and a corresponding data representation inthe signal samples.
 5. The device as claimed in claim 3, furthercomprising a masking unit configured for masking respectivenon-indicative entities in the transmitted signal sequence, wherein thedata processing detector is further configured for classifying entitiesinto one of an indicative state and a non-indicative state.
 6. Thedevice as claimed in claim 3, wherein the signal samples are encodedunder consideration of a signal space convention applying a color model,wherein an applied signal space comprises complementary channels forrepresenting the entities forming the signal samples, wherein respectivecomponents of the entities are related to respective complementarychannels of the signal space.
 7. The device as claimed in claim 6,wherein the signal space comprises a color representation basicallyindependent of illumination variations.
 8. The device as claimed inclaim 1, wherein the descriptive model is a skin color model describingskin representation under consideration of signal space conventions, andwherein the descriptive model is at least one of a non-parametric skinmodel and a parametric skin model.
 9. The device as claimed in claim 5,wherein the masking unit is further configured for processing theindicative entities such that the at least one vital parameter issubstantially detectable in the transmitted signal sequence, whereinnon-indicative side information represented by the indicative entitiesis at least partially attenuated in the transmitted signal sequence. 10.The device as claimed in claim 9, wherein the masking unit is furtherconfigured for blurring sets of indicative entities in the signalsamples, wherein average characteristics of the indicative entitiesremain substantially unchanged, such that such that the at least onevital parameter of interest is substantially preserved in thetransmitted signal sequence.
 11. The device as claimed in claim 1,further comprising a database providing a plurality of descriptivemodels attributable to an influence parameter selected from the groupconsisting of skin color type, ethnic region, ethnic group, body region,sex, sensor unit characteristics, and illumination conditions, andcombinations thereof.
 12. The device as claimed in claim 1, wherein thesignal detector unit is further configured for adapting the presentdescriptive model under consideration of an influence parameter selectedfrom the group consisting of skin color type, ethnic region, ethnicgroup, body region, sex, sensor unit characteristics, and illuminationconditions, and combinations thereof.
 13. The device as claimed in claim1, further comprising a sensor unit configured for sensingelectromagnetic radiation at a distance, wherein the sensor unit iscoupled to the signal detector unit such that non-indicative entities inthe input signal are basically disregarded when transmitting respectivesignal samples.
 14. The device as claimed in claim 1, further comprisinga feature detector configured for detecting identity-related prominentfeatures in the signal samples of the input sequence, and a featuremasking unit configured for masking respective entities in thetransmitted signal sequence.
 15. The device as claimed in claim 1,wherein the processing unit is further configured as aphotoplethysmographic processing unit capable of extracting the at leastone vital parameter of interest from the sequence of transmittedsamples, wherein the at least one vital parameter can be extracted underconsideration of vascular activity represented by skin color properties.16. A device for processing data derivable from remotely detectedelectromagnetic radiation emitted or reflected by a subject, the datacomprising physiological information, comprising: a signal detectormeans configured for receiving an input signal and for transmittingindicative entities thereof, the indicative entities being indicative ofphysiological information representative of at least one vital parameterin a subject of interest; and a processing means configured forextracting the at least one vital parameter from a transmitted signalcomprising the indicative entities; wherein the at least one vitalparameter is extracted under consideration of detected skin colorproperties representing circulatory activity; wherein the input signalcomprises an input sequence of signal samples; wherein the signaldetector means comprises at least one data processing detectorconfigured for processing respective signal samples of the inputsequence under consideration of spectral information embedded in signalsample entities, thereby generating a transmitted signal sequence; andwherein the signal detector means is further configured for detectingthe indicative entities under consideration of at least one defineddescriptive model describing a relation between physical skin appearancecharacteristics and a corresponding representation in the input signalsuch that non-indicative side information represented by non-indicativeentities in the input signal is substantially undetectable in theresulting transmitted signal.
 17. The device as claimed in claim 16,further comprising: a masking means configured for masking respectivenon-indicative entities in the transmitted signal sequence; wherein thedata processing detector is further configured for classifying entitiesinto one of an indicative state and a non-indicative state; and whereinthe masking means is further configured for processing the indicativeentities such that the at least one vital parameter is substantiallydetectable in the transmitted signal sequence and that non-indicativeside information represented by the indicative entities is at leastpartially attenuated in the transmitted signal sequence.
 18. A methodfor processing data derivable from remotely detected electromagneticradiation emitted or reflected by a subject, the data comprisingphysiological information, comprising the steps of: receiving an inputsignal and transmitting indicative entities thereof, the indicativeentities being indicative of physiological information representative ofat least one vital parameter in a subject of interest; detecting theindicative entities under consideration of at least one defineddescriptive model describing a relation between physical skin appearancecharacteristics and a corresponding representation in the input signalsuch that non-indicative side information represented by non-indicativeentities in the input signal is substantially undetectable in aresulting transmitted signal; and extracting the at least one vitalparameter from the transmitted signal comprising the indicativeentities, wherein the at least one vital parameter is extracted underconsideration of detected skin color properties representing circulatoryactivity.
 19. The method as claimed in claim 18, wherein the inputsignal comprises an input sequence of signal samples, and whereindetecting the indicative entities comprises: processing respectivesignal samples of the input sequence under consideration of spectralinformation embedded in signal sample entities, thereby generating atransmitted signal sequence; and detecting the indicative entities underconsideration of the at least one descriptive model describing arelation between physical appearance characteristics and a correspondingdata representation in the signal samples.
 20. A computer readablenon-transitory medium having instructions stored thereon which, whencarried out on a computer, cause the computer to perform the steps ofthe method as claimed in claim 18.